Conventionally, inventions for searching and recommending a content such as a television program or a piece of music based on a liking of a client (so-called content personalization) have been proposed (for example, refer to Patent Document 1). For the content personalization, a method called cooperative filtering (CF) and a method called content based filtering (CBF) are used widely.
Also a service of providing a piece of music conforming to the feeling of a user to the user has been proposed. For example, a system as been proposed wherein, if a request for a piece of music which a user wants to enjoy when the user is happy is issued, then a piece of music which is decided as being happy is selected and provided to the user.    [Patent Document 1] Japanese Patent Laid-Open No. 2004-194107